Process of treating textile fiber



Patented Aug. 25, 1942 PROCESS OF TREATING TEXTILE FIBER Robert William Maxw ell, Wilmington, DeL, as-

signor to E. L-du Pont de Nemours & Company,

Wilmington, Del.,

a corporation of Delaware No Drawing. Application October 15, 1940,

Serial No. 361,286

8 Claims.

This invention relates to a process for modifying the surface characteristics of textile 'materials, and particularly to bestowing upon the same a soft feel and the quality of water-repellency. It is an object of this invention to provide a process for achieving the above ends by the aid of relatively inexpensive reagents involving a relatively simple mode of treatment. Other and further objects of this invention will appear as the description proceeds.

Unmodified synthetic or natural textile fibers as a whole are not Water-repellent, and waterrepellency is an unnatural but desirable property for them. It has been known to the art for many years that fabrics or yarns can be rendered waterrepellent by treatment with waxy materials, but practically all the older treatments have suffered from lack of resistance to laundering or drycleaning. The new water-repellent agents and treatments that have been developed in recent years give water-repellent properties which are resistant to laundering but most of these agents are based on expensive chemicals and sometimes require involved or complicated treatment. In this invention, a simple treatment has been developed in which the use of readily accessible chemicals to give water-repellent properties durable toward laundering is involved.

Now according to this invention,- the surface characteristics of textile material are modified, in the sense that the material is rendered soft to feel and water-repellent, by treatment with carboxylic acid esters of hydroxamic acids, containing an aliphatic chain of at least 9 carbon atoms. In other words, the textile material is treated with an agent having the general formula wherein R is an organic radical containing in its structure an aliphatic chain of at least 9 carbon atoms and may contain additional groups as herein defined; R is a short-chain alkyl radical, for instance methyl orethyl; while Z such as sodium or potassium, or an acyl group such as acetyl. As typical illustrations of compounds falling within the above general formula may be mentioned at this poin the acetic acid ester of palmitohydroxamic acid, which may have one-of the tautomeric forms:

o /OH CnHar-C and CuHar-C NH-O-G 0-0113 N0c0.cin the N acetyl or O-acetyl derivative of the same:

o o cocm C15Ha1C or (Julia-C NHOC O.CH3 N 0c0.cm H3Cl30 and the reaction product of the same ester with sodium, which may be assigned one of the tautomeric formulas From a strict viewpoint, the general formula of the compounds employed in this invention should be written wherein all the symbols have the same significance as above, while the bracket designates that the expression gained member Z (which stands for hydrogen, an alkalimetal or an acyl group) may be attached to either the O-atom or the N-atom. It is customary however in chemistry, capa 1e of existing nate but one of the tautomers, it being understood that the other cluded by inference. In view of the simplicity of thereby, this. conventional method will. be adhered to hereinafter in the specification and some of the claims, -it being un- I derstood that no intent to limit thls inventlonis stands for hydrogen or a substituent capable of replacing the hydrogen in a hydroxamic acid compound. Thus, Z may be an alkali-metal,

'of impregnatingt to be implied'therein. I

The treatment afo mentioned usually consists fabric with-a solution of the the selected hydroxamic acid,

selected ester when dealing with compounds j in tautomeric form, to desigtautomer is automatically inremoving the excess liquid from the fiber, and then subjecting the latter to a heat treatment, generally referred to as baking, at a temperature sufficient to decompose the hydroxamic compound with resultant water-repellent effect upon the fiber. This temperature may vary from 90 to 200 C., but will more commonly be included in the range of 100 to 1'10 C.

The impregnation may be effected by means of a solution of the hydroxamic ester in an organic solvent or by means of an aqueous suspension thereof effected by the aid of emulsifying or dispersing agents. ployed, the solvent should preferably be an unreactive, non-hydroxylated, anhydrous solvent, for example, benzene, toluene or carbon tetrachloride. In the case of thesodio-ecompounds of the hydroxamic ester, alcoholic solutions may also be employed with good results. In either event, it is desirable to dry the fabric thoroughly before treatment, as this minimizes loss of reagent due to side reactions.

The reagent selected may also be applied by spraying a solution thereof onto the fabric. It can also be applied in undiluted form at temperatures above its melting point (provided the latter does not exceed 100 0.), but this is not a preferred procedure. The reagent should not in any event be applied at a temperature higher than 150 C., as cellulosic fiber is apt to be tendered at such higher temperature.

After impregnation the excess liquid is removed by squeezing between rolls, centrifuging or air drying, until the fiber contains substantially its own weight or twice its own weight of solution.

The baking step may follow in general the details of procedure employed with the known water-repellency agents of the permanent class, for instance the acylamidomethyl quaternary salts, and may vary in duration from /2 minute for the higher temperatures to 30 minutes for the lower ones.

Without limiting my invention to any particular procedure, the following examples in which parts by weight are given, will serve to illustrate my preferred mode of operation.

EXAMPLE 1 N-acetomy-lauramide Analysis:

Calculated for C11H2a-CONHOCOCH3:

N=5.45% Found: N=5.28%

(b) Treatment of fabric Cotton Jean cloth was dipped into a solution of the above obtained N-acetoxy-lauramide in benzene. The cloth was then squeezed to remove excess liqui dried in a current of air and then baked for five minutes at 160 treated cloth showed a fair degree of waterrepellency which, however, was improved af er laundering.

(g. Preparation of Where organic solutions are em- The rise in water-repellent quality by laundering is to be explained by the hypothesis that, in accordance with the behavior of other permanent water-repellency agents, for instance the acylamido quaternary ammonium salts or the acyl isocyanates, the hydroxamic esters employed in this invention decompose during the baking step liberating a long-chain aliphatic radical which either reacts with the fiber or reacts with other radicals of its kind to produce compounds which are adsorbed on the fiber. At the same time, the decomposition produces simple acids or salts which may become loosely adsorbed unto the fiber, exerting thereon a wetting action, which offsets partially the water-repellency action of the other decomposition products deposited.

Upon laundering, the water-soluble salts are washed away, leaving the other decomposition products and allowing them to exert their full water-repellency eflects. It will be understood, however, that the above hypothesis is advanced merely to facilitate understanding of the disclosure without any intent to limit my invention thereby.

The laundering mentioned in this example and hereinbelow was effected by boiling the cloth for 1 hour in an aqueous bath containing 0.1% of Ivory soap.

EXAMPLE 2 (a) Preparation of N-acetoxy-palmitamide 3 parts of palmitohydroxamic acid (C15H31CONH-.-OH) and 3 parts of acetic anhydride are mixed and warmed on the steam bath for ten minutes. At the end of this time, the product does not give the ferric chloride test, indicating complete acetylation. Upon cooling, the crystalline mass is filtered, washed with petroleum ether and dried. The N-acetoxy-palmitamide obtained melts at 76 to 80 C.

Analysis:

Calculated for C15H31-CONHO-COCH32 (b) Treatment of fabric (a) Preparation of N-acetyl-N-acetoaypalmttamide 6 parts of palmitohydroxamic acid and 40 parts of acetic anhydride were heated together at 70 C. until the mixture became clear. The, mass was then cooled, and the reaction product separated in fine, white needles, which were filtered off and washed with petroleum ether. The nitrogen analysis of this product indicated that it was most probably an acetyl derivative of the compound obtained in Example 2, corresponding to one of the tautomeric formulas CHEM-C O-NOC 0 CH3 and CnHax-U-O-COCH: CH; 0 -0-oocm aaoae44 (b) Treatment of fabric parts of the reaction product obtained in Part a were dissolved in 100 parts of ethyl alcohol -(95% strength), and cotton broadcloth was dipped into thissolution. After soaking for 5 minutes, the cloth samples were wrung out, dried in a current of air and baked at 120 C. for minutes. The cloth exhibited a fair degree of water-repellency both before and after laundering.

EXAMPLE 4 (a) Preparation of sodzo-N-acetoxy-palmitamide Samples of cotton broadcloth were steeped for 5 minutes in the methyl alcoholic solution of sodio-N-acetoxy-palmitamide obtained in Part a above, and were then wrung out and dried in a current of air. The samples were then baked variously at temperatures and time periods varying from 5 minutes at 170 C. to 40 minutes at After rinsing with Ivory soap solution, all samples showed a water-repellency rating of 1 by the "spot test," which is the highest rating obtainable by this test and is assumed to correspond to 100% water-repellency.

In lieu of the acetic acid ester of palmitohydroxamic acid above, a carboxylic acid derivative of any other long-chain hydroxamic acid may be converted into its sodio derivative by the same process with an equally beneficialefiect upon its powers as a water-repellency agent. It appears thus that the replacement of the residual hydrogen atom on the CO.N group of the acyl hydroxylamine compound by sodium increases considerably the efiectiveness of this type of compound as a water-repellency agent.

It will be understood that although I used cotton fabrics in the above examplesby way of illustration, my invention is applicable also to other textile materials whether of cellulosic, animal or artificial origin; for instance, cellulose acetate, regenerated cellulose, linen, wool, silk, nylon. Furthermore, it is applicable also to cellulosic material in non-fibrous form, such as Cellophane, as well as to leather, wood and similar materials.

In lieu of the hydroxamic acid derivatives employed in the above examples, any other carboxylic-acid derivative of a hydroxamic acid may be employed, provided the latter contains an aliphatic chain of at least 9 carbon atoms, and

preferably 9 to 27 carbon atoms. As practical examples of such hydroxamic acids may be mentioned those derived from lauric, myristic, palmitic, stearic or oleic acid; eicosanoic (020), docosanoic (C22), carnaubic (C24) or-cerotic (C26) acid; hexadecen-9-oic (palmitolelc) acid; also branched-chain and cycloaliphatic acids, for instance hydro-abietic and omega-cyclohexyl-v dodecanoic acids.

Di-hydroxamic acids derived from dibasic carboxylic acids may also be employed, for instance those derived from the dibasic acids of the formula COOII COOH wherein n stands for an integer from 9 to 22.

As regards the carboxylic acid forming the ester portion of the molecule, it should preferably be a short chain aliphatic compound, for instance acetic or propionic acid.

As practical additional examples of hydroxamic esters falling withinthe scope of this invention, may be mentioned the following:

N,N'-diacetyl-N,N-diacetoxy hexadecamethylene-diamide: I

Disodio- N,N' dipropionoxy decamethylene-diamide:

(CHOW CO-IF-O-C O CHICHI The said bis-compounds may be prepared by adding to a suspension of one mole of the corresponding bis-hydroxamic acid in a suitable solvent, for instance dioxane, about 2.2 moles of acetic anhydride, and refluxing the mixture for 2 hours or more.

In the preferred practice of this invention, the material under treatment is steeped in a 0.5 to 5% solution of the selected compound, in an inert solvent at room temperature. One to several minutes of soaking usually suflices for penetration, or one ormore immersions in the solution adequately wets'the fabric. The excess solution 5 is conveniently removed by wringing, centrifuging, drying in a current of air, or any other well known procedure, care being observed to eliminate any fire hazard from combustible organic solvents. In general, any liquid which is a solvent for and chemically inert toward the repellent agent under the conditions of the process may be used. Specific solvents suitable for this use include petroleum naphtha, carbon tetrachloride, chloroform, trlchloroethylene, tetra-' chloroethylene, ethylene dichloride, pentachloroethane, hexachloroethane, benzene, toluene, dioxane, diethyl ether, diisopropyl ether, ethyl acetate, 1,3-dichlorobenzene, ligroin, gasoline, and

. above treatment, the fabric generally acquires a pleasant, soft feel. If desired, the concentration of the treating solution may be considerably less than 0.5%, in which case no water-repellent effect or but a very weak water-repellent effect will be obtained. This treatment is, however, sufficient to impart a soft feel to the fabric, and this effect is permanent in the sense that it is not destroyed by laundering. Concentrations even as low as 0.01% have proven effective for this purpose.

My novel treatment with the water-repellency agents of this invention may be carried out in conjunction with other treating agents or processes, provided there are no groups present of a second agent that will react with the N-acyloxy group of the compound. Such materials as resins, softening agents, textile sizes, and finishing agents answering the above restrictions can be used to advantage. The treatments may be applied simultaneously, but preferably consecutively, in creaseproofing processes.

Many other variations in details of procedure will be apparent to those skilled in this art, without departing from the spirit of this invention.

I claim:

1. A process of treating textile material for the purpose of modifying its surface characteristics, which comprises impregnating the same with a carboxylic ester of a hydroxamic acid containing in the hydroxamic radical an aliphatic chain of at least 9 carbon atoms, and subjecting the impregnated material to the action of dry heat at a temperature between 90 and 200 C.

2. A process of treating textile material for the purpose of modifying its surface characteristics, which comprises impregnating the same with an ester compound of the general formula as herein defined; R is a lower alkyl radical; while Z stands for a member of the group consisting of hydrogen, the alkali metals, and acyl radicals; and subjecting the impregnated material to the action of dry heat at a temperature between and 200 C. y

3. A process of treating textile material for the purpose of modifying its surface characteristics, which comprises impregnating the same with wherein R is an alkyl radical containing from 9 to 27 carbon atoms, R is a lower alkyl radical, while Z stands for a member of the group consisting of hydrogen, the alkali-metals, and acyl radicals; and subjecting the impregnated material to the action of dry heat at a temperature between and C.

4. A process of treating textile material for the purpose of modifying its surface characteristics, which comprises impregnating the same with the reaction product of sodium methylate with a carboxylic acid ester of a hydroxamic acid containing an aliphatic chain of at least 9 carbon atoms; and subjecting the impregnated material to the action of dry heat at a temperature between 100 and 170 C.

5. A process of treating textile material for the purpose of modifying its surface characteristics, which comprises impregnating the same with an organic solution of a compound of the general formula Na wherein R is an alkyl radical having from 9 to 2'7 carbon atoms, while R is a short-chain alkyl radical; removing the excess solution from the fabric, and subjecting the latter to baking at a temperature between 100 and 170 C.

6. In the process of treating cellulosic textile fiber for the purpose of rendering the same'water-repell'ent, the step which comprises impregnating the fiber with N-acetoxy-palmitamide.

'7. In the process of treating cellulosic textile fiber for the purpose of rendering the same water-repellent, the step which comprises impregnating the fiber with sodio-N-acetoxy-palmit amide.

8. The process of treating cellulosic textile fiber for the purpose of rendering the same water-repellent, which comprises treating the same with an alcoholic solution of sodio-N-acetoxypalmitamide, of 0.5 to 5% strength; removing excess solution from the fiber, and subjecting the latter to a baking treatment at a temperature between 100 and 170 C. for a period of time ranging from 5 to 40 minutes.

ROBERT WILLIAM 

